SUMMARY Loss of dopaminergic neurons is the principal cellular pathology underlying Parkinson's disease (PD). A fundamental but unresolved challenge is how to replenish dopaminergic neurons and restore the neurotransmitter dopamine-regulated neural circuits. Transplantation of dopaminergic neurons into the striatum can reverse behavioral deficits of PD, highlighting the therapeutic value of striatal dopamine. However, the efficacy of transplanted stem cells is limited by the survival and integration of induced neurons, as well as, the potential for tumorigenesis. The long-term goal of this proposal is to define a new regenerative strategy for neuronal induction using patient-specific endogenous glial cells. Our preliminary results show that resident glia can be in vivo reprogrammed into neuroblasts in the adult striatum. These neuroblasts proliferate and generate mature neurons when supplied with neurotrophic factors or the small chemical compounds valproic acid. Most importantly, the newly generated striatal neurons can functionally integrate into local neuronal circuits. Three aims are proposed in this application to further analyze and optimize the in vivo reprogramming process: 1) to optimize the reprogramming process for the generation of dopaminergic neurons, 2) to functionally characterize these induced dopaminergic neurons in the adult brain, and 3) to examine translatability of induced dopaminergic neurons. The results of this work may lead to an entirely novel treatment paradigm for PD.